Today, electronic grade silicon and solar cell silicon are mainly produced by decomposition of trichlorosilane (HSiCl3) or monosilane (SiH4). HSiCl3 is conventionally produced by reacting metallurgical grade silicon with HCl at temperatures in the range 300° C. to 1100° C. This process has a number of disadvantages. Several other compounds, particularly silicon tetrachloride SiCl4, are produced in the process, causing reduced yield of HSiCl3. Furthermore, due to the temperature requirement of about 1000-1100° C., the decomposition process of HSiCl3 to silicon is characterized by low yield and large energy consumption. Moreover, during decomposition the reactor has to be cooled to prevent deposition of solid silicon on the reactor walls. Finally, due to the highly corrosive atmosphere, corrosion of the reactor is common.
The decomposition of monosilane into silicon is a far less energy demanding process with high yield. The decomposition takes place at a temperature as low as about 460° C. In the use of monosilane for production of electronic or solar cell grade silicon, the main problems are difficulties encountered in the production of monosilane gas. Today, the most common way of producing monosilane is a disproportionation process starting with HSiCl3, but the yield of this process is low. Thus, there is a need for improved methods of producing monosilane.